1. Field of the Invention
The present invention relates generally to vehicle suspension systems and, more particularly, to a means for, and method of, mounting a truck suspension member to a truck axle housing.
2. Discussion
The subject invention finds particular utility in the heavy, medium and light duty truck and trailer industry. In this industry, common suspension installations have for a long time featured axles attached to single leaf spring assemblies.
Recently, the use of air-ride beam-type suspensions in the truck and trailer industry has become quite popular. Such suspensions come in various forms. Generally speaking, however, they include a pair of longitudinally extending flexible beams, one each of which is located adjacent to one of the two longitudinal side frame rails located underneath the body of the truck or trailer chassis. These beams, sometimes called main support members, Z-beams or gooseneck springs, are then pivotally connected at one end to the frame hanger that is attached to the adjacent frame rail of the vehicle. Spaced along the beam at a distance from the frame hanger is an air bag (bellows) and an axle. Examples of this type of suspension are the Hendrickson HA/HAS series suspension and the suspension disclosed in Snyder U.S. Pat. No. 5,346,247 issued Sep. 13, 1994.
In such air-ride beam-type suspensions, a square axle housing is typically secured to each main support member by clamping the axle housing using a bracket assembly comprised of a pair of U-bolts, a top pad, an axle seat, a bottom cap and attaching nuts. In such an arrangement, the main support member is clamped between the top pad and the axle seat while the axle housing is clamped between the axle seat and the bottom cap. The U-bolts typically pass over the top pad and through the bottom cap and clamp the entire assembly together via the attaching nuts.
While the use of such bracket assemblies to attach truck axles to suspension members has proven for a long time to be effective, the clamping load exerted upon the axle housing by the top seat and bottom cap is tremendous. As a result, the relatively thin-walled axle housing will yield to some degree which results in a required retorquing of the attaching nuts on the U-bolts in the field every 15,000 miles or so of truck usage.
Furthermore, due to the sensitivity of the axle housing to the magnitude of the clamping force, proper detailed torque-up procedures for installation and maintenance are desirable. If the compressing clamp load of the U-bolts is not properly performed when the suspension is installed or during maintenance, the axle housing could become overstressed due to the dynamic loads introduced during operation, and seriously deform. As a result, the clamp assembly would loosen if not retorqued and eventually come apart.
It is thus desirable to have an axle bracket assembly that removes the clamping compressive forces from the axle housing. By removing the yielding member (the axle housing) from the clamping forces exerted by the U-bolts, the necessity of retorquing the attaching nuts on the U-bolts in the field would be minimized or even possibly eliminated all together.
A further disadvantage of existing bracket assemblies is that they feature many separate parts. The multitude of parts increases the difficulty of handling and installation. The technician or serviceman is forced to keep track of, handle and align during assembly the many different parts. It would save the technician or serviceman valuable time if he or she were able just to handle a main support member that could be bolted as-is to the axle.
Adjustment of the axle pinion angle with existing bracket assemblies can also prove to be difficult. Because the top of the axle housing is seated in a top seat and the bottom of the axle housing is seated in a bottom seat, both the top seat and bottom cap must be specifically designed and coordinated with one another in order to obtain the proper axle pinion angle. It would thus be desirable to have an axle bracket assembly that more easily adapts to various pinion angle installations.
Accordingly, an object of the invention is to provide a system of mounting suspension members on vehicle axles so that minimal or no compressive forces are exerted upon the axle housings.
Another object of the invention is to provide a system of mounting suspension members on vehicle axles which offers ease of handling and installation.
Still another object of the invention is to provide a system of mounting suspension members on vehicle axles which easily adapts to various pinion angles.